BirdAnalyst
Species · Delaware · BBS 2025 Release · 1966–2024

Field Sparrow Population Trend in Delaware

All statesGeneralists

Field Sparrow in Delaware has fallen sharply: down 54% on the route-weighted index since 1968.

-54%Since 1968TrendPercent change in the route-weighted abundance index between a smoothed baseline window and the most recent one. It tracks direction, not absolute population.Full methodology →
17Routes In StateSurvey routesHow many standard-protocol BBS routes contributed counts. More routes means a steadier, better-sampled index; very thin coverage is suppressed.Full methodology →
58YearsYears surveyedNumber of years with at least one standard-protocol run in this geography. A longer record makes the trend more reliable.Full methodology →

Notable Field Sparrow Trends in DelawareNotable signalsLong-arc shifts the engine flags automatically — sustained declines or increases large enough to stand out from year-to-year noise.Full methodology →

long arc declinecomputed indexTrend sourceWhether the figure is our own computed route-weighted index or an official USGS modeled estimate. The current build labels every trend as computed.Full methodology →

Field Sparrow has fallen sharply in Delaware: down 54% on the route-weighted index since 1968.

Field Sparrow Population Forecast in Delaware

If the recent trend holds, Field Sparrow in Delaware is projected to fall about 68% by 2029 — from 7.8 in 2024 to a central estimate of 2.5 (95% range 0.00–7.6). A 5-year backtest shows a typical error of ±58.5%, with 60% of held-out values landing inside the 95% band.

-68%Change by 2029TrendPercent change in the route-weighted abundance index between a smoothed baseline window and the most recent one. It tracks direction, not absolute population.Full methodology →
2.5Projected 2029 indexProjected indexThe central forecast of the abundance index if the recent trend continues. A projection of the current trajectory, not a prediction.Full methodology →
0.00–7.695% range95% rangeThe 95% uncertainty band around the projection at the forecast horizon. The true value should land inside it most of the time.Full methodology →
±58.5%Backtest errorBacktest errorTypical error when we hold out the most recent years, forecast them, and compare to what actually happened. Lower means a more trustworthy projection.Full methodology →
If the recent trend holds, Field Sparrow in Delaware is projected to fall about 68% by 2029 — from 7.8 in 2024 to a central estimate of 2.5 (95% range 0.00–7.6). A 5-year backtest shows a typical error of ±58.5%, with 60% of held-out values landing inside the 95% band.19662029
Projection of the recent trend (dashed) with 80/95% bands — a projection, not a prediction. Habitat, climate, and land use are not modeled.
YearProjected indexProjected indexThe central forecast of the abundance index if the recent trend continues. A projection of the current trajectory, not a prediction.Full methodology →95% low95% rangeThe 95% uncertainty band around the projection at the forecast horizon. The true value should land inside it most of the time.Full methodology →95% high95% rangeThe 95% uncertainty band around the projection at the forecast horizon. The true value should land inside it most of the time.Full methodology →
20253.10.008.2
20262.90.008.1
20272.80.007.9
20282.60.007.8
20292.50.007.6

Field Sparrow Survey Routes in Delaware

Routes recording Field Sparrow in Delaware.
Recent countThe raw number of individuals recorded on this route in its most recent survey year. A single-route tally, not a trend.Full methodology →
Blackbird1720241994
Lowes Xrds1219911966
Millsboro720242017
Holleyville 2720242006
Holleyville620041966
Harrington420241966
Frankford420121966
Milton420161966
Pepperbox420161998
Pepperbox 2420242017
Wilmington320141966
Bethany Bch319891966
Milton 2320172017
Mt Pleasant220191966
Frederica220141966
Dover219851966
Georgetown220221992

Field Sparrow Population Trend in Other States

alabamaarkansascoloradoconnecticutfloridageorgiaillinoisindianaiowakansaskentuckylouisianamainemarylandmassachusettsmichiganminnesotamississippimissourimontananebraskanew-hampshirenew-jerseynew-yorknorth-carolinanorth-dakotaohiooklahomapennsylvaniarhode-islandsouth-carolinasouth-dakotatennesseetexasvermontvirginiawest-virginiawisconsinwyoming

Source: USGS North American Breeding Bird Survey, retrieved 2026-05-22.